If you're really after a good browsing experience, phone, 3G and WiFi in a single device then I'd recommend an iPhone 3G. The drawbacks of this device is that it's not open source is locked to AT&T if you live in the USA.

Personally I go with the 2 device combo as others here have recommended. My N810 works very well with my Sony Ericsson K850i phone at HSDPA speeds.